package cc.laop.utils;

import java.util.Date;
import java.util.Random;
import java.util.UUID;

import org.apache.commons.lang3.time.DateUtils;

public class RandomUtils {
	public static String[] chars = { "a", "b", "c", "d", "e", "f", "g", "h",
			"i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u",
			"v", "w", "x", "y", "z", "0", "1", "2", "3", "4", "5", "6", "7",
			"8", "9", "A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K",
			"L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X",
			"Y", "Z" };

	public static String[] nums = { "1", "2", "3", "4", "5", "6", "7", "8",
			"9", "0" };

	public static String shortUuid() {
		StringBuffer shortBuffer = new StringBuffer();
		String uuid = RandomUtils.uuid();
		for (int i = 0; i < 8; i++) {
			String str = uuid.substring(i * 4, i * 4 + 4);
			int x = Integer.parseInt(str, 16);
			shortBuffer.append(chars[(x % 62)]);
		}
		return shortBuffer.toString();
	}

	public static String randomCode() {
		return randomCode(4);
	}

	public static String randomCode(int length) {
		Random random = new Random();
		StringBuffer str = new StringBuffer();
		for (int i = 0; i < length; i++) {
			int index = random.nextInt(chars.length);
			str.append(chars[index]);
		}
		return str.toString();
	}

	public static String randomNum(int length) {
		Random random = new Random();
		StringBuffer str = new StringBuffer();
		for (int i = 0; i < length; i++) {
			int index = random.nextInt(nums.length);
			str.append(nums[index]);
		}
		return str.toString();
	}

	public static Date randomDate(int days) {
		Random random = new Random();
		int differ = random.nextInt(days);
		Date date = new Date();
		return DateUtils.addDays(date, -differ);
	}
	
	public static String uuid() {
		return UUID.randomUUID().toString().replace("-", "");
	}
}
